Persistent Vomiting and Epigastric Pain in an Adolescent: A Case of Superior Mesenteric Artery Syndrome Unmasked

<b>Background and Clinical Significance:</b> Superior mesenteric artery syndrome (SMAS) is a rare and often underdiagnosed cause of proximal intestinal obstruction, resulting from compression of the third portion of the duodenum between the SMA and the aorta. It typically occurs in individuals with significant weight loss due to mesenteric fat depletion. <b>Case</b><b>Presentation:</b> We report the case of a 14.5-year-old female presented with a 6-day history of intractable vomiting and epigastric pain, on a background of intermittent vomiting over the preceding six months associated with a 7 kg unintentional weight loss, culminating in inability to tolerate oral intake. Her clinical course was complicated by a transient episode of blurred vision, numbness, and incoherent speech, initially suspected to be a neurological event. Extensive gastrointestinal and neurological investigations were inconclusive. Elevated fecal calprotectin levels raised suspicion for inflammatory bowel disease, given her family history, though endoscopy and histopathology were unremarkable. Advanced imaging ultimately demonstrated a markedly reduced aortomesenteric angle (6°) and distance (4 mm), confirming the diagnosis of SMAS. The patient was initially managed conservatively with total parenteral nutrition (TPN), achieving partial weight gain of 5 kg after 8 weeks of TPN. Due to persistent duodenal compression, surgical intervention was required. At 7-month follow-up, the patient remained symptom-free with restored nutritional status and a good weight gain. <b>Conclusions</b><b>:</b> This case highlights the importance of considering SMAS in adolescents with chronic upper gastrointestinal symptoms and significant weight loss. Early recognition and appropriate imaging are essential to diagnosis, and timely surgical management can lead to excellent outcomes when conservative treatment is insufficient.